1. Field of the Invention
The present invention relates to a single focus lens that is suitable for use in small apparatus having an imaging function such as cell phones with a camera, PDAs (personal digital assistants), and digital still cameras.
2. Description of Background Art
Imaging apparatus such as digital still cameras employ an imaging device such as a CCD (charge-coupled device) sensor or a CMOS (complementary metal oxide semiconductor) sensor. In recent years, such imaging devices have been miniaturized to a large extent. Accordingly, imaging apparatus main bodies and lenses mounted thereon have come to be required to be reduced in size and weight. On the other hand, in recent years, imaging devices having a large number of pixels have been developed to attain high image quality and, accordingly, lens systems have come to be required to be high in such performance as resolution and contrast.
An example of imaging lenses used in such imaging apparatus is one disclosed in JP-A-10-48516. JP-A-10-48516 discloses an imaging lens consisting of first to third lenses that are arranged in this order from the object side (three-lens system). In this imaging lens, the first lens is small in power and an aperture stop is disposed between the second lens and the third lens.
As described above, recent imaging devices have been miniaturized and increased in the number of pixels and, accordingly, imaging lenses have come to be required to exhibit a high resolution and be high in the degree of compactness. Although the imaging lens of JP-A-10-48516 attains certain levels of performance and compactness with a small number of lenses (three lens system), development of a more compact, higher-performance lens system is desired.